This section introduces aspects that may help facilitate a better understanding of the disclosure. Accordingly, these statements are to be read in this light and are not to be understood as admissions about what is or is not prior art
While graphene's excellent electrical properties, i.e., high mobility, has attracted a great deal of interest in the scientific community, the apparent absence of a bandgap for graphene has limited its application realm considerably. At the same time, it is the missing of a bandgap that provides graphene with its ambipolar device characteristics and the substantially nonexistence of a true device off-state.
As a result, some scientists have been working on how the advantageous electronic properties of graphene can be utilized while dealing appropriately with its unique characteristics rather than enforcing conventional device concepts.
Frequency multiplication is one of the common approaches for signal generation that is required in a large number of applications, e.g. digital/analog communication, terahertz radio astronomy, and remote sensing. In conventional applications, frequency multiplication is achieved through modulation of a sinusoidal signal by means of nonlinear electronic components such as diodes or conventional field effect transistors (FETs). In this way harmonics at higher frequencies are generated, and the harmonic component of interest is then extracted employing appropriate filter designs. For various purposes, frequency multipliers built for all multiplication factors are desirable. However, while a frequency “doubler” is known and can be built by utilizing the nonlinear current-voltage properties of a diode, building a frequency “tripler” is more challenging and uncommon, since the modulated output signal of a conventional tripler tends to be dominated by the fundamental frequency component with relatively small power at the third harmonic frequency. The resulting poor output spectral purity (generally <15%) of the third harmonic component in turn limits the conversion efficiency resulting in complicated filter designs.
Therefore, there is an unmet need for a frequency tripler design that does not suffer from the aforementioned limitations.